Distribution and ecology of the Banks Peninsula tree weta, Hemideina ricta : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University

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Massey University
Comparative morphology. Hemideina ricta and H.femorata were assessed for their morphological similarity. H. ricta adults were found to have significantly longer and wider heads in both sexes and longer cerci in adult males. The tibial length of adult female H. femorata was significantly longer than in H. ricta. Thorax width, thorax length and ovipositor length did not differ significantly between the two species. Habitat and distribution. H. ricta and H.femorata are predominantly allopatric on Banks Peninsula, with H. ricta being found on the outer eastern portion of Banks Peninsula and on the inner Akaroa Harbour while H. femorata is located on the inner Akaroa Harbour and westward from here. The two species overlapped altitudinally, but H. femorata was not found above 450 m asl whereas H. ricta was discovered from 20 m to 806 m asl. H. femorata showed a strong preference for kanuka habitat whilst H. ricta had a broader preference for kanuka, mixed broadleaved hardwoods, fallen totara and broadleaf logs and old fenceposts. Refuge occupation. The refuges where H. ricta and H.femorata rested during the day were assessed for their similarity. Both species preferred galleries formed by beetle larvae as these probably offered the greatest protection from predators. Weta were also found in splits, under the bark of trees, in rotten logs and in the forks of trees. Significantly more galleries were occupied by H. ricta adults, compared to juveniles, that occupied areas under bark and in splits. There was no significant difference in the refuges occupied by adult and juvenile H.femorata. Behaviour. The nocturnal behaviour of H. ricta in captivity and in the field was investigated. Their activity in captivity was significantly greater. H. ricta were observed moulting, ovipositing, mating and fighting in captivity whereas in the field none or only a few of these activities were recorded. H. ricta in captivity also spent more time perching on logs and foliage compared to field situations. It is probable that temperature influenced this result because H. ricta showed elevated activity and a greater variety of activity with increased temperature in the field. Feeding preferences. The comparative feeding preferences of H. ricta and H. femorata were assessed on five commonly located mixed broadleaved hardwood tree species. H. ricta and H. femorata consumed significantly different amounts of the selected plants as did juvenile and adult weta. More Parsonsia was eaten by H. ricta and more Pittosporum was eaten by H. femorata. In addition, significantly more Parsonsia was consumed by adult male H. ricta compared to juvenile males. There was no significant difference between preferred plant between the sexes.
New Zealand, Banks Peninsula District, Tree wetas, Hemideina ricta, Wetas